Pneumatic bulk trailer



Oct. 13, 1964 A. ANDERSON ETAL PNEUMATIC BULK TRAILER '3 Sheets-Sheet 1 FilQd April 11, 1960 BY a g ATTORNEY.

hrlllllllll Oct. 13, 1964 A. l. ANDERSON ETAL 3,152,342

PNEUMATIC BULK TRAILER 3 Sheets- Sheet 2 Filed April 11, 1960 0 v, mg E 0 r N T 2.6 R Z w V mo r m g A A. l. ANDERSON ETAL 3,152,842

PNEUMATIC BULK TRAILER Oct. 13, 1964 Filed April 11. 1960 3 Sheets-Sheet 3 Kare/ Kom'aek A TTORNEK United States Patent 3,152,842 PNEUMATKC BULK TRAILER Arthur I. Anderson, tit, Paul, and Karel Konieek, Minneapolis, Minn, assignors to Butler Mwufacturing Company, Kansas City, Mo., a corporation of Missouri Filed Apr. M, 196%, Ser. No. 21,162

16 Claims. {CL 302-53) This invention relates generally to the transporting and handling of pulverulent or finely divided'materials in bulk form, and refers more particularly to novel apparatus for the purposes set forth.

One general object of the invention is to provide a vehicle capable of transporting and rapidly discharging to great heights and over relatively great distances various pulverulent or finely divided materials as, for example, dry cement, chemicals, food products, and the like, the discharge being accomplished by pneumatic means. While we are aware that pneumatic handling of bulk materials is not, in and of itself, new, the present invention presents an improved arrangement by which the material is caused to flow more readily into and through the transit or discharge line, and which results in complete clean-out of the transport body without requiring extensive fiuidization of the contents through the medium of air slides or the like.

, Another object of the invention is to provide a strong yet easily manufactured transport vehicle which is capable of quick conversion from use with pulverulent or finely divided solids to the transporting of various liquids.

Still another object of the invention is to provide an arrangement for a transport vehicle for the purposes set forth in which the internal structure of the vehicle is so compartmented as to promote rapid and effective cleanout of the solids, yet in which the partitions which form the compartments are subjected to relatively light loads, and thus can be manufactured and assembled of light weight and relatively low strength materials.

Yet another object of the invention is to produce an integrated container and pneumatic unloading arrangement in wliiclnunder certain conditions of operation, pressurized air accumulated within the container can be utilized for the purposes of assisting in unclogging and cleaning out of the discharge lines.

A further object of the invention is to provide a vehicle body equipped with pneumatic unloading means whereby substantially continuous flow of the finely divided material is obtained, with the material in such condition as to be easily transmitted by air pressure through the dis charge line. It is a feature of the invention that the proper conditioning of the material is obtained with low air volumes, thus permitting the use of a relatively small compressor.

Other and further objects of the invention together with the features of novelty appurtenant thereto will appear in the course of the following description.

In the accompanying drawings which form a part of the instant specification and are to be read in conjunction therewith, and in which like reference numerals indicate like parts in the various views;

FIG. 1 is a side elevational view of a typical transport vehicle embodying the features of our invention, parts being broken away for purposes of illustration;

FIG. 2 is a greatly enlarged fragmentary elevation of the forward hopper and adjacent lower part of the vehicle body, parts being broken away and in section for purposes of illustration; 7

FIG. 3 is.a sectional view taken along the line 33 of FIG. 2 in the direction of the arrows, parts again broken away for purposes of illustration;

FIG. 4 is an enlarged fragmentary sectional view taken along the line 4-4 of FIG. 2 in the direction of the arrows;

FIG. 5 is a schematic view showing the vehicle body in crosssection at one of the reinforcing rings, illustrating the arrangement of the pneumatic system therewith;

FIG. 6 is a sectional view taken along the line 66 of FIG. 1 in the direction of the arrows;

FIG. 7 is a sectional view taken along the line 7-7 of FIG. 1 in the direction of the arrows;

FIG. 8 is a horizontal section looking downwardly from the inside through a hopper equipped with a modified air diffuser arrangement and showing the means of communieating air thereto;

FIGS. 9 and 9a are enlarged sectional views taken perspectively along the lines 99 of FIG. 8, and 9a-9a of PEG. 9 in the direction of the arrows;

FIG. 10 is a view similar to FIG. 8, but illustrating a further modification of the air diffuser and arrangement within the hopper;

FIG. 11 is an enlarged view taken along line lit-11 of FIG. 10 in the direction of the arrows; and

FIG. 12 is a further enlarged side view of portion of the diffuser of FIGS. 10 and 1 1, parts being shown in longitudinal section to illustrate the details of construction.

Referring now to the drawings, the unit selected for illustrating and describing the invention comprises a trailer body 2% adapted to be drawn behind a conventional tractor, the rear wheels of which are shown at 21. The tractor has the usual chassis 22 supporting a fifth wheel assembly 23 through which connection with the trailer is established. The details of the tractor and fifth wheel assembly play no part in the invention, and consequently will not be further described.

The trailer body is in the formof a horizontally disposed tank of circular cross-section having the domed forward end 24 and a similarly domed rearward end 25. The forward section 29a of the tank is of lesser diameter than the somewhat longer rearward section 20b, and is joined therewith by a frusto conical section 200 through the medium of butt Welds 30 (see FIG. 2) at the adjoining ends. The rearward end of the trailer is supported on and carried by a carriage 26 having tandem Wheels 27. The carriage may be of any suitable and well-known type, and in the illustrated embodiment is so arranged as to provide a rearwardly extending platform on which can be mounted a suitable heavy duty blower 28 and power means 2? therefor.

The main section 2912 of the trailer body can conveniently be manufactured of shorter cylindrical lengths placed end to end and butt welded. Circumscribing the exterior of the tank are a plurality of ring-like members, these being separately identified for the purposes of description by reference numerals 31, 32, 33 and 34, respectively. The ring elements are identical with each other, each being generally U-shaped in cross-section with the spaced legs welded at their edges directly to the tank body (FIG. 2), and the web spaced from the tank body thus to form a closed annularpas'sageway extending completely around the periphery of the tank. To permit periodic drainage from the rings of condensate or other liquids which may become trapped therein, each ring is provided with a drain aperature at its lowermost point normally closed by a removable plug 35. While the rings serve one important purpose in strengthening the tank body, they also have equally important functions as air conduits, as will later be made clear.

The top of the tank body is provided with one or more filler necks 36 which have removable sealable covers or caps 37, many types of which are presently available on the market and are well-known. The only requirement for the covers is that they provide an air-tight seal when secured in closed condition.

Positioned at the bottom of the body section 2012 and arranged in spaced fore and aft relationship with one another are three identical discharge hoppers H, H and I The number of hoppers provided will obviously depend primarily on the length of the section 2015. Each hopper is preferably in the shape of an inverted four-sided pyramid having the four converging planar walls 38, 39, 4t and 41 which terminate at the lower end at a discharge conduit .2. The individual hoppers fit within and depend below suitable openings in the tank body, side Walls 38 and 46 being joined by welding with the opposite side edges of its opening as at 43 (FIG. 3) and the fore and aft walls 39 and 41 extending upwardly inside the tank past the fore and aft edges of the tank opening (FIG. 2). The fore and aft edges of the opening are formed to lie closely adjacent the walls 39 and 41 and are welded thereto by a continuous seam weld as at 44 to provide a fluid-tight connection.

Again referring to FIGS. 2 and 3, and also to FEGS. 6 and 7, it will be noted that the forward wall 3 of the front hopper H joins and forms the lower portion of an inclined partition 45 which serves to segregate the space above the hoppers from the forward portion of the trailer body. A similar partition 46 is located near the rear endof the body, it likewise being joined to the rear wall 41 of the rearmost hopper H" to close off a space between the partition and wall 25. The partitions 45 and 46 both terminate at their upper ends in vertically disposed portions dSa or 46a. The edges of the partitions are shaped to conform to the inside contour of the tank and are welded thereto. As a consequence, dry materials which are introduced through the filler necks 36 are confined to the space between the partitions, leaving those volumes between the tank end walls 24 and 25 and the respective partitions void.

It is important to satisfactory unloading of the unit to have the incline of the partitions at no greater than approximately 50 with the vertical so that material will freely flow downwardly therealong toward the hoppers. The hopper walls should be at an even steeper pitch, say, no more than 46 from the vertical.

The fore and aft end walls 39 and 41 of the central hopper H are joined with the corresponding adjacent walls of the front and back hoppers H and H" in the manner illustrated in FIG. 2. In each case the walls intersect to form a ridge 47 and are welded by a continuous weld running from one side of the tank to the other. Material is thus diverted into one hopper or the other and cannot fall intothat portion of the tank beneath the ridge. While FIG. 2 shows only the connection between the front and central hoppers H and H, the same arrangement is employed between the central and back hoppers.

The side walls of the hoppers H, H and H" are each reinforced by a strengthening member 46 which appropriately may be a channel section having its legs welded directly to the side wall with the web spaced from the side wall. The side walls of the hoppers are further tied together through the medium of a tube or pipe 49 extending transversely across the hopper and projecting through and welded to suitable apertures in the side walls. The ends of the tube are secured, preferably by welding, to parallel angle members 59 which extend fore and aft on the outside of the tank and which are similarly welded thereto.

Turning now to a consideration of the interior of the hoppers, it will be observed that each hopper has positioned on the inside surfaces of the side walls 38 and 40 a plurality of air diffuser elements 51. In the preferred embodiment, elements 51 are arranged on each wall in two rows of three each, the rows being parallel with the corners of the hopper and closely adjacent thereto.

The construction of the elements 51 may conveniently d be that shown and described in Schemm Patent 2,665,035. While reference may be had to that patent for more specific details, generally each element 51 comprises a rectangular base plate 52 joined at its edges with a fiattened dome-like perforate metal partition 53 which forms with the base plate a plenum chamber 54. The partition 53 is covered with a woven fabric envelope 55, the specifications for which are set forth in the aforementioned patent. The elements 51 are each centered on an individual aperture 56 therefor in the adjacent side wall with the base plate engaging and sealing against a suitable gasket 57 surrounding the opening. Connected with and projecting centrally from each base plate outwardly through its aperture 56 is an air conducting tube 58. The tube 58 opens at its inner end in the plenum 54 and is provided with a side port 58a intermediate its ends. The outer end of the tube is threaded and extends through a suitable aperture in the outer wall 66a of a manifold 60 which will presently be described in greater detail. Nuts 61 and washer 61a on the outer end portion of tube 58 serve to firmly draw the base plate 51 into sealing engagement with gasket 57 and to secure the element 57 in place in the hopper while providing a seal around the tube where it passes through manifold wall 69a. The outer end of each tube 53 is closed as by a cap nut 53b.

Each manifold 60 comprises simply an elongate rectangular box-like structure disposed against and welded to an outside wall of the hopper and serving a row of elements 51. An air input nipple 63 is provided on each manifold and connected with the nipple is an air hose 64 which leads from the air supply system now to be described.

Returning for a moment to FIG. 1, and also referring to FIG. 5, it will be observed that leading from the discharge of compressor 28 forwardly along one side of the tank body is the pressure line 65. Line 65 leads through a check valve 66 to a T 67 from which departs a branch pipe 68 parallel with the tank body and adjacent the hoppers near the upper edges thereof. As may be seen from FIG. 3, a second branch pipe 68a lies on the opposite side of the hoppers from branch 68. It is connected with branch 68 by means of a cross-over conduit 69 which passes laterally beneath the tank body between the hoppers. The air hoses 64 which are connected with the respective diffuser manifolds 60 take off from the branches 68 and 68a.

Interposed in line 65 below the T 67 is a manually controllable flow regulator valve 76 which may be of any construction permitting variable iiow between full open and full closed. Line '65 continues beyond the flow regulator valve to form a material discharge portion 71 which passes adjacent the lower ends of the hoppers. Connection between the hoppers and the material discharge line 71 is established by the short discharge conduits 42 leading from the hoppers (FIGS. 2 and 3). Each conduit 42. is fitted with a suitable valve 72, 72' or 72" which may be a butterfly valve having the operating handle 73, 73' or 73". Under conditions of pneumatic unloading, the discharge 71a of line 71 will be connected with a suitable conduit or hose D for conducting the material to the selected storage area.

As earlier mentioned, in our invention the tank rings 31 and 34 play a part in the over-all air operation and pressure distribution system. Referring first to FIG. 7, it will be noted that pressure within the tank body at the top thereof is communicated to the interior of ring 31 through an aperture 74. A similar aperture 75 is provided at the bottom of the tank wall so as to establish communication between the inside of the ring and the void portion of the tank behind partition 46. Since apertures 74 and 75 remain open at all times, obviously the air pressure on opposite sides of partition 46 will be equal, the ring 31 serving as the path for continuous pressure communication from one side of the partition to the other. The same arrangement of apertures, in

' at 2 psi.

a 5 this case 74' and 75, are provided in connection with ring 34- (FIGS. 2 and 6) to keep the pressure equalized on opposite sides of partition 45.

For purposes to be explained later, ring 31 also has connected with it a bleed line 76 having check valve 77 permitting flow only in a direction away from the ring. Bleed line 76 connects with the air pressure line ahead of the air regulator valve 67 (see FIG. 5). Ringfil also serves as a convenient take-off for a line 78 to a pressure relief valve 79 and a tank pressure indicator gauge 80. A similar gauge'Sl is provided for visibly indicating the pressure on the downstream side of air regulator valve 70. Both gauges should be mounted in a single housing 82 supported in any desired way below the tank body as shown in FIG. 1, so as to make it easy to maintain surveillance over both gauges with one glance.

In the use of the unit for the handling and unloading of finely divided or pulverulent solids it will be understood that the hopper valves 72, 72' and 72" are all initially closed and that the solids are introduced to the tank body with any suitable handling equipment through one or more of the filler necks 36. Ordinarily loading will be discontinued before the material level reaches the top of the tank body, a typical filled level being shown at L in FIG. 5. During loading and also when in transit, no use is made of the pneumatic system, the blower 28 and its drive not being started until time for unloading.

To commence unloading the following procedure is followed. First, the usual transit or discharge hose D is coupled with the discharge end 71a of the materials discharge line 71. The covers 37 are inspected to see that they are tightly sealed. The air regulator valve 70 is then preferably fully opened and the blower motor started. When the blower has reached operating speed the air regulator valve 70 is then slowly closed, thus causing the air from the blower to flow directly into the tank body through branch lines68 and 68a, hose connections 64, and the air diffuser elements 51. The air, being introduced at the bottom of the load, percolates upwardly through the material and in doing so is believed to precondition and aerate it sufi'iciently to materially improve its handling and flow characteristics.

When the pressure within the tank (as read on gauge 80) reaches the desired level (which we have found to be in the neighborhood of l2to lbs. p.s.i.) regulator valve 70 is cracked open to set up flow through the discharge line 71, the pressure there being initially set The system is now ready for introduction of the solids into the discharge line through which a continuous stream of air is moving.

Discharge is accomplished sequentially from the three hoppers, the usual procedure being to start it with the central hopper H. To institute feeding of the material from the tank, valve 72 is opened. The substantial pressure differential which initially exists between the interior of the tank and the discharge line (10-13 p.s.i.

against 2 p.s.i.) coupled with the agitating effect of the air which passes through the diffuser elements 51 and is diverted downwardly into the discharge line insures of immediate flow of material into the discharge line. Once solid material enters the discharge linev the pressure therein will rise due to increased resistance to flow. By virtue of the air connections it will be evident that the system is such that the pressure in the tank will at no time be less than that in the line and usually will remain slightly above the line pressure in line 71, particularly in the open area above the level of the material. Thus, the static pressure within the tank and above the material continues to exert a force upon it tending to force it downwardly toward the outlets and thispressure is assisted by the air introduced at the diffuser elements 51 to maintain free flow of the material into the line 71 from whence it is blown to discharge.

When'the level of material in the central portion of t5 the tank descends to the point where it is within the upper portion of the hopper H, a notable reduction in the pressure in line 71 willbe observed on gauge 81. Thus, when the pressure reaches approximately 7-8 p.s.i., as observed on gauge 79, valve 72' should be closed and the valve 72" opened to permit flow of material into the line from hopper H". The opening of the valve 72 should be rather slow in order to permit a gentle build-up of volumetric flow of solids from hopper H". The line pressure will again return to the running pressure as in the course of unloading from the central hopper.

Unloading through hopper H" is continued until it is completely empty, which is reflected by a decrease in line pressure to about 2 p.s.i. The steep pitch of the partition 46 insures that all of the material above hopper H will flow into the hopper and be discharged through line 71.

When hopper H is completely empty, as reflected by the drop in pressure to approximately 2 p.s.i., valve 72" is closed and valve 72 on the forward hopper is opened. As in the preceding cases, material will commence to flow into the line 71. Emptying of hopper H will be refiected by the pressure in line 71 again dropping to 2 p.s.i., at which time valve 72 is closed and valve 72' again opened to clean out the remaining material which may be lodged in the central hopper H.

Referring again to FIG. 5, the arrangement of the air system, particularly with reference to the connection established between the ring 31 and the line 65, insures that in the event of compressor failure during unloading, the large volume of compressed air accumulated within the tank will be available for discharge into line 63 to be applied to the material in the materials discharge line 71 and hose D to continue the movement of the material therethrough.

If the compressor should fail, the discharge valve 72, 72', or 72", whichever one is open at that instant, is closed. The compressed air within the tank flows out of the tank through apertures 74 and 75 into ring 31 and thence into line 65 and on into the discharge line 71. The check valve 66 prevents loss of pressure in the direction of the blower, and thus the only path of escape is through the materials discharge line 71. Flow under the influence of the accumulated pressure in the tank will continue until the line resistance to flow equals the pressure exerted by the accumulated air in the tank or until the line is empty. Unless there is a clog in the discharge hose, the volume of compressed air within the tank is ordinarily more than sufiicient to result in complete purging of the hose. This insures that in restarting, the normal operating procedures can be followed, or that if desired, the unit can be uncoupled and removed for repair without leaving residual matter in the discharge hose.

The air system embodied in our invention also provides an arrangement wherein the volume of air supplied'by the blower can be supplemented with the large volume of compressed air in the tank body to assist in slug removal. It is possible that, with some materials, a slug will occasionally form in the discharge line 71, or the hose connected therewith, and offer sufiicient resistance to continued flow as to be beyond the capacity of the blower alone to clear it. If this should occur, the following procedure is employed.

First, the valve 72, 72 or 72", whichever is open, is closed. The regulator valve is then fully opened. The pressure within the tank (and consequently in the discharge line 69) is reduced to approximately 2 p.s.i. by bleeding air from the tank, this being accomplished preferably by manually opening the pressure relief valve 79. When the pressure reaches 2 p.s.i., the air regulator valve 7ft is then closed, leaving the pressure in the discharge line 70 at 2 p.s.i., and the pressure relief valve is returned to its normal condition so that pressure will commence to again build up in the tank. When the pressure in the tank reaches 15 psi. (which we will assume is the maximum capacity of the compressor), the regulator valve 7% is quickly thrown to full open. This results in a quick surge of air into the line 71 elow valve 70. The increased supply of air at 15 psi. provided by the tank body has the etfect of tremendously decreasing the time interval required for the pressure in the line 69 to build up again to 15 p.s.i. as compared with the interval which would result from using the compressor alone, and consequently produces a sharp impact on the slug which is more likely to break it up than in the case of gradual pressure build-up through the use of the compressor alone. Successive impacts on the slug can be obtained by repeating the procedure outlined above. It will be evident that if the slug clears, the system will return to normal operation Without further adjustment, except that the air regulator valve is again partially closed to throttle the flow into line 71.

From the foregoing it will be evident that the unit is admirably suited for the hauling and unloading of finely divided and pulverulent solids of many types. However, it is also readily convertible to storage and transporting of liquids with a few simple mechanical adjustments being required.

In order to render the entire internal volume of the tank body available for reception of liquids, the partitions 45 and 46 are provided with openings in their upper portions 45a or 4611 which are normally closed by bolted and sealed cover plates 45b or 46b. Similar cover plates 9i) cover openings 91 in those portions of the end walls 39 and 41 of hoppers H and 1-1", respectively, immediately above the tank bottom. FIG. 2 illustrates the cover plate 90 for the end wall 39 of hopper H, and it will be understood that a similar cover plate is provided on the oppositely extending end wall 41 of hopper H which joins with partition 46. By simply removing the cover plates, liquid is now free to circulate into all portions of the tank, the upper openings in the portions 45a and 46a of the partitions permitting pressure venting as the liquid level rises.

Before utilizing the transport for liquid hauling, the air diffuser elements 51 are removed and the apertures 56 in the hopper walls sealed by any suitable means, for example, a double disk closure in which the disks can be clamped toward one another to seal the openings on opposite sides of the hopper wall. Naturally, the discharge of liquids from the tank will be by gravity or by suitable pumping equipment, the same valves 72, 72' and 72" being utilized for controlling discharge through line 69. The air regulator valve 7t) will remain closed in order to prevent the entry of liquid into the air conduits.

Return of the unit to condition for transporting solids is accomplished by replacingthe covers 45!), 46b and 90, and the return to the positions illustrated of the air diffusing elements 51.

FIGS. 8, 9 and 10 illustrate a modified construction through which conversion of the unit to hauling of fluids is facilitated. The principal advantage of the modified arrangement is that the diffusers are installed as removable assemblies which require no perforation of the hopper wall and which can be quickly removed to accommodate conversion of the unit to liquids.

The diffuser elements 151 in. the modified construction are identical to those previously described and are mounted in rows of three at the corners of the hopper. The diffuser elements of each row are carried by a filler plate 101 which lies longitudinally along an inside corner of the hopper and straddles same with its central portion spaced inwardly well away from the corner. The longitudinal edges of the plate 191 are formed with inturned flanges 101a which engage and rest against the hopper walls on opposite sides of the corner.

Secured to the underside of plate 101 and extending lengthwise thereof is a manifold structure 160 which may be identical to the manifold 69 of the preceding embodiment except that in this case the edges are welded to plate 1511 rather than the side wall of the hopper. In other words, in the modified construction the manifolds are located within the hopper and on the undersides of the plates 101.

The base plate 152 of each diffuser element is disposed on the face of plate 101 and located between the two is a suitable sealing gasket 157. The air tube 158 extends through plate 101 through a suitable opening 156 and into and through the manifold 160, passing through the outer wall 1641a of the latter through a suitable aperture provided therein. The outer end of each air tube is closed by a cap nut 1555b and the air port 158a in each tube communicates with the interior of the manifold. As in the preceding embodiment the diffuser element is tightened down on gasket 157 by means of a nut 161 on the threaded outer end of the tube, a washer 161a serving to provide a seal around the tube where it passes through the outer Wall of the manifold.

An air inlet nipple 105 is secured to plate 191 and communicates with the interior of manifold 160. A hose 1% connects at one end with nipple 105, the other end of the hose leading to a nipple 149a formed on the hollow crosspipe 14$ which is like that described in the earlier embodiment. Whereas as in the earlier embodiment, the crosspipe 149 serves no purpose other than as a strengthener for the hopper structure, in the modified construction it serves as a conduit for the air from the branch pipes 163 and 168a being connected therewith by suitable fittings. The branch pipes 163 and 16811 are connected with the air system in the same fashion as pipes 68 and 63a of the earlier embodiment.

Each air diffuser assembly is supported within the hopper by a tension arrangement which includes the hook-like lugs H17 and 108 secured to the inside of the hopper in the corners thereof. The upper end of plate 101 is provided with a bail 109 which hooks over the upper lug, while the lower end of the plate is provided with the tension spring 110 having a hook portion 119a which is engaged with the lower lug. Installation and removal of the air diffuser assembly is accomplished simply by disengaging the springs and bail from the lug and disconnecting the air hoses 106 from nipples 149a. To seal the cross-pipe 149 against entry of liquid, a simple plug can be inserted in each nipple.

FIGS. 10, 11 and 12 illustrate a still further modification of the hopper and air diffuser assembly. 'Here the air diffuser 200 comprises a perforated central tube 201 over which is sleeved a fabric 262 of the type earlier described. The lower end of tube 201 is closed by a plug 203 having an eye thereon for reception of a spring 204. The other end of spring 2194 is provided witha hook portion 2114a adapted to engage over a lug 235 secured to the hopper in one corner thereof adjacent the bottom. The upper end of tube 201 is likewise plugged with a plug 2% into which leads an elbow 2117 which communicates with the interior of the tube. A bail 208 is secured to the elbow and engages with the hook-like portion of an upper lug 209 likewise secured in place in the hopper. A flexible hose Z111 connects with elbow 2G7 and leads to the crosspipe 249 which is arranged with air pipes 268 and 268a as in the previous embodiment.

It will be evident that as in the preceding embodiment there are no connections between the air diffusers and the hopper other than as provided by the spring and hail connection. Consequently, it is a simple matter either to install or remove the diffuser elements through simple stretching of the springs and disengagement of the spring or hail from the lug to which it is attached.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

g It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as i1- lustrative and not in a limiting sense.

Having thus described our invention, we claim:

1. In a materials handling system with pneumatic unloading means, the combination of a horizontally disposed, elongate hollow body with opposed end walls, means forming a materials discharge opening in the bottom of the body with one lateral edge of the opening spaced longitudinally from the nearest end wall of the body, a partition subdividing the interior of said body and joined with said one edge and extending upwardly therefrom at an incline toward said nearest end wall, means for pressurizing that part of the interior of said body in communication with said opening, and means on the exterior of the body forming a passageway running from near the top of the body across the plane of the partition and communicating with the interior of the body on opposite sides of the partition whereby to equalize the pressure in the body above and below said partition, said last named means comprising an annular ring surrounding said body with openings through the body wall into the ring above and below said partition.

2. In a materials handling system with pneumatic unloading means, the combination of a horizontally disposed, elongate hollow body with opposed end walls, means forming a materials discharge hopper on the bottom of the body with one edge of the hopper spaced longitudinally from the nearest end wall of the body, a partition subdividing the interior of said body and joined with said one edge and extending upwardly therefrom at an incline toward said nearest end wall, air diffuser elements mounted within said hopper, blower means for supplying air under pressure, conduit means from said blower to said diffuser elements whereby to introduce air into said body in the vicinity of said hopper, and means on the exterior of the body forming a passageway running from near the top of the body across the plane of the partition and communicating with the interior of the body on opposite sides of the partition whereby to equalize the pressure in the body above and below the partition, said last named means comprising an annular ring surrounding said. body with openings through the body wall into the ring above and below said partition.

3. In a materials handling system with pneumatic unloading means, the combination of a horizontally disposed, elongate hollow body with opposed end walls, at least one discharge hopper positioned intermediate the ends of said body on the lower side thereof and communicating with the interior of said body, one lateral edge of the hopper being spaced longitudinally from the nearest end wall of the body, a partition subdividing the interior of said body and joined with said one edge and extending upwardly therefrom at an incline toward said nearest end wall, means for pressurizing the air in that part of the interior of said body in communication with said hopper, and means on the exterior of the body forming a passageway running from near the top of the body across the plane of the partition and communicating with the interior of the body on opposite sides of the partition whereby to equalize the pressure in the body on opposite sides of the partition, said last named means comprising an annular ring surrounding said body with openings through the body well into the ring above and below said partition. a

4. In a materials handling system with pneumatic unloading means, the combination of a horizontally disposed, elongate hollow body with opposed end walls, at least one discharge hopper positioned intermediate the lid- ends of said body on the lower side thereof and communicating with the interior or" said body, one edge of the hopper being spaced longitudinally from the nearest end wall of the transport body, a partition subdividing the interior of said body and joined with said one edge and extending upwardly therefrom at an incline toward said nearest end wall, air diiluser elements mounted within said hopper, blower means for supplying air under pressure, conduit means from said blower means to said diffuser elements whereby to introduce air into said body in the vicinity of said hopper, a materials discharge line passing adjacent said hopper and connected with said conduit means, said hopper provided with an outlet connected with said discharge line, air regulator means between said conduit means and said discharge line operable to throttle flow through the discharge line and maintain a positive pressure differential between the interior or" the body and the discharge line, means on the exterior of the body forming a passageway running from the top of the body across the plane or" the partition and communicating with the interior of the body on opposite sides of the partition whereby to equalize the pressure in the body above and below the partition, and air bleed means communicating between said passageway and said conduit means ahead of said regulator means, said bleed means including a check valve preventing flow from said conduit means back toward said passageway.

5. The combination as in claim 4 including a check valve in said conduit means between said blower means and air bleed means.

6. In a materials handling system equipped with pneumatic unloading means, the combination of a hollow storage body having a bottom outlet, a materials discharge line passing adjacent said outlet and having a lateral connection therewith intermediate its ends, valve means interposed between said outlet and said discharge line to control flow of material from said body to said discharge line, blower means for supplying air under pressure, conduit means connecting said blower means with said discharge line, air regulator means between said conduit means and said discharge line for varying the air flow through the latter, means for conducting air from said conduit means into the lower portion of said body adjacent said outlet, air passage means connecting the space in the upper portion of the body with said conduit ahead of said air regulator means, said passage means including a check valve permitting flow in the direction from the body to the conduit only and means in said conduit between said blower means and the connection with said air passage means for preventing flow back toward the blower.

7. In a materials handling system equipped with pneumatic unloading means, the combination of a horizontally disposed, elongate hollow body of generally circular cross section and having opposed end walls, a ring like member coaxial with said body and surrounding and secured to said body on the exterior thereof intermediate said end walls and providing an air passageway running from the upper portion of the body to the lower portion, said body including an opening in the upper portion com municating with said passageway whereby said ring like member provides a conduit for air from the upper portion toward the lower portion on the exterior of the body while reinforcing the wall of said body.

8. In a materials handling system equipped with pneumatic unloading means, the combination of a hollow storage body, a materials discharge line having an air input end and a materials discharge end, means connecting the lower portion of the interior of said body laterally with said discharge line between said ends whereby to provide a passageway for flow of materials from said body into said discharge line, valve means interposed in said passageway and operable to open and close said passageway, blower means for supplying air under pressure, conduit means connecting said blower means with said air input end of said discharge line, air regulator means ahead of said input end operable to vary the air flow from said blower means through said discharge line, means connecting a point in said conduit means ahead of said air regulator means with the lower portion of said body whereby to provide an open path for air from said blower means to the interior of said body, and air passage means connecting the upper interior portion of the body with said conduit means ahead of said air regulator means, said air passage means including a check valve permitting flow in the direction from the body to the conduit only.

9. A combination as in claim 8 including means in said conduit means between the blower means and the connection with the air passage means for preventing flow back toward the blower means.

10. A combination as in claim 8 including means selectively operable to open communication between the in terior of the body and the surrounding atmosphere.

11. In a materials handling system with pneumatic unloading means, the combination of a hollow storage body, at least one discharge hopper on the lower portion of said body and communicating with the interior of said body, air diffuser elements mounted within said hopper, blower means for supplying air under pressure, conduit means from said blower means to said diffuser elements whereby to introduce air into said body through said diffuser elements, a materials discharge line passing adjacent said hopper and connected with said conduit means, said hopper provided with an outlet connected with said discharge line, air regulator means between said conduit means and said discharge line operable to throttle flow through the discharge line and maintain a positive pressure differential between the interior of the body and the discharge line, and air passage means connecting the upper interior portion of said body with said conduit means ahead of said air regulator means, said air passage means including a check valve permitting flow in the direction from the body to the conduit only.

12. In a materials handling system with pneumatic unloading means, the combination of a hollow storage body having a bottom, at least two laterally spaced discharge hoppers connected with said bottom and communicating with the interior of said body throgh correspondingly spaced openings in the bottom of the body, each hopper terminating at its lower end in a materials outlet, a materials discharge line connected with said outlets, blower means for supplying air under pressure, air diffuser means mounted in each said hopper, conduit means connected with said blower means and including air conducting means providing open communication from said blower means to each of said difiuser means whereby to introduce air from said blower means to said body through said respective diffuser means, means connecting said conduit means with said discharge line downstream of said air conducting means and including air regulator means operable to vary the flow of air from said conduit means to said discharge line and maintain a positive pressure differential between the interior of said body and said discharge line, and valve means interposed between each said outlet and said materials discharge line and selectively operable to control the flow of material from the respective hoppers to said discharge line.

13. In a materials handling system with pneumatic unloading means, the combination of a generally cylindrical horizontally disposed elongate hollow body with opposed end walls, at least t-wo tapered discharge hoppers positioned intermediate the ends of said body and depending from the lower side thereof and communicating with the interior of said body, said hoppers spaced from one another longitudinally of said body, each hopper terminating at its lower end in a materials outlet, a discharge line extending past said hoppers and provided with lateral connections with said outlets intermediate its ends, valve means interposed between each said outlet and said discharge line and selectively operable to open and close communication between the respective outlets and said discharge line, blower means for supplying air under pressure, conduit means connecting said blower means with one end of said discharge line, air regulator means associated with said discharge line and operable to variably control the flow of air therethrough at a point ahead of said lateral connections, air diffuser means in each hopper, and air conducting means connecting said conduit means ahead of said regulator means with each of said difiuser means whereby to provide open communication between said conduit means and each of-said diffuser means thereby to permit entry of air from said blower means to said body through either of said diffuser means.

14. The combination as in claim 13 wherein said diffuser means comprises aplurality of air dilfusing elements within said hopper having air diffusing surfaces, said elements spaced from one another around the inside of the hopper, connecting means associated with said elements and operable to releasably connect same with the hopper Walls, and means detachably coupling said difiuser elements with said air conducting means.

15. The combination as in claim 14 wherein said diffusing elements include elongate air receiving sections mounted with their long axes oriented in the direction of taper of the hopper.

16. The combination as in clainr 13 including a materials divider between said hoppers inside said body forming intersecting materials guiding surfaces which lead to the respective hoppers and which define a transverse ridge between the hoppers.

References .Cited in the file of this patent UNITED STATES PATENTS 2,027,697 Nielsen Jan. 14, 1936 2,030,553 Tiley Feb. 11, 1936 2,190,727 McKenna Feb. 20, 1940 2,393,932 Petroe Jan. 29, 1946 2,524,919 Meincke Oct. 10, 1950 2,565,835 Adams Aug. 28, 1951 2,580,215 Bozich Dec. 25, 1951 2,715,550 Shields Aug. 16, 1955 2,734,782 Galle Feb. 14, 1956 2,794,686 Anselman June 4, 1957 2,915,340 Lusted Dec. 1, 1959 2,919,159 La Croix Dec. 29, 1959 2,924,489 Beckmann Feb. 9, 1960 FOREIGN PATENTS 1,230,526 France Apr. 4, 1960 

1. IN A MATERIALS HANDLING SYSTEM WITH PNEUMATIC UNLOADING MEANS, THE COMBINATION OF A HORIZONTALLY DISPOSED, ELONGATE HOLLOW BODY WITH OPPOSED END WALLS, MEANS FORMING A MATERIALS DISCHARGE OPENING IN THE BOTTOM OF THE BODY WITH ONE LATERAL EDGE OF THE OPENING SPACED LONGITUDINALLY FROM THE NEAREST END WALL OF THE BODY, A PARTITION SUBDIVIDING THE INTERIOR OF SAID BODY AND JOINED WITH SAID ONE EDGE AND EXTENDING UPWARDLY THEREFROM AT AN INCLINE TOWARD SAID NEAREST END WALL, MEANS FOR PRESSURIZING THAT PART OF THE INTERIOR OF SAID BODY IN COMMUNICATION WITH SAID OPENING, AND MEANS ON THE EXTERIOR OF THE BODY FORMING A PASSAGEWAY RUNNING FROM NEAR THE TOP OF THE BODY ACROSS THE PLANE OF THE PARTITION AND COMMUNICATING WITH THE INTERIOR OF THE BODY ON OPPOSITE SIDES OF THE PARTITION WHEREBY TO EQUALIZE THE PRESSURE IN THE BODY ABOVE AND BELOW SAID PARTITION SAID LAST NAMED MEANS COMPRISING AN ANNULAR RING SURROUNDING SAID BODY WITH OPENINGS THROUGH THE BODY WALL INTO THE RING ABOVE AND BELOW SAID PARTITION. 